More and more people have become aware of the dangers of excessive fructose in diet. Dietary fructose is present primarily in added dietary sugars, honey, and fruit. Americans most frequently ingest fructose from sucrose, a disaccharide containing 50% fructose and 50% glucose bonded together, and high fructose corn syrup (HFCS), a mixture of free fructose and free glucose, usually in a 55/45 proportion.

With the introduction of HFCS in the 1970s, an increased intake of fructose has occurred and obesity rates have risen simultaneously. There is also increasing evidence that fructose may play a role in hypertension and renal disease. Dr. Johnson and Dr. Nakagawa recommend that low protein diets include an attempt to restrict added sugars containing fructose.